class_docstr: Interface for implementing a Trial Scheduler class.
  
  Note to Tune developers: If a new scheduler is added, please update
  `air/_internal/usage.py`.
docstr: Returns a human readable message for printing to the console.
docstr_tok: ["Returns","a","human","readable","message","for","printing","to","the","console","."]
code: def debug_string(self) -> str:
      """Returns a human readable message for printing to the console."""
  
      raise NotImplementedError
  
imports: from typing import Dict, Optional, TYPE_CHECKING
  from ray.air._internal.usage import tag_scheduler
  from ray.tune.result import DEFAULT_METRIC
  from ray.tune.experiment import Trial
  from ray.util.annotations import DeveloperAPI, PublicAPI
label_desc: Use image node_id 11 for calling the TrialScheduler obj's underlying member method code with example usage: obj.debug_string() without return types